Incandescent lamp.



N'. -639,|6|. Patented' mm.l l2, |899. R. A. FESSENDEN. mcANnEscENT LAMP.

(Application mea Aug. 7, 1899.)

(No Modem 2 shets-sheex gw wm Patented Dec. I2, |899.

R. A. FESSENDEN. INCAND-.ESCENT LAMP.

(No Model.)

(Application filed Aug. 7, 1899.)

2 Sheets-*Sheet 2.

FISE- INVENTOR,

Att'y.

/Iumwnms PETERS co. Hman-mo., wAsmNomN, n4 C.,

UNITED STATES PATENT OFFICE.

REGINALD A. FESSENDEN, OF ALLEGIIENY, PENNSYLVANIA, ASSIGNOR OF ONE-HALF TO GRANT MCOARGO, OF PITTSBURG, PENNSYLVANIA.

INCANDESCENT LAMP.

SPECIFICATION forming part of Letters Patent No. 639,161, dated December 12, 1899.

Application filed August 7, 1899. Serial No. 726,395. (No model.)

T @ZZ zutont it Hefty conce/vt:

Be it known that I, REGINALD A. FnssnN- DEN, a citizen of the United States, residing at Allegheny, in the county of Allegheny and State of Pennsylvania, have invented or discovered certain new and useful Improvements in Incandescent Lamps, of which improvements the following is a specification.

The invention described herein relates to 1o certain improvements in that class or kind of incandescent lamps known as the Nernst lamp, in which is used arod or pencil formed of a material capable of serving as an electric conductor only when heated. This form of lamp has never come into practical commercial use on account of the difficulty experienced and the delay involved in the preliminary heating of the rod or pencil.

The object of the present invention is to zo provide for the practical instantaneous heating of the pencil, the heating and the closing of the controlling-switch being nearly simultaneous, as the hea-tingis effected by the current employed for rendering the pencil inz 5 candescent.

The invention is hereinafter more fully described and claimed.

In the accompanying drawings, forming a part of this specification, Figure I is a sec- 3o tional elevation of myilnproved lamp. Fig. 2 is a similar view taken on a plane at right angles to the plane of section of Fig. I; and Fig. 3 is a detail view, on an enlarged scale, of the rod or pencil.

In the practice of my invention a shaft l is mounted in suitable bearings 2 in the sides of the supporting or protecting shell, which is preferably made approximately hemispherical and has its inner surface highly polished, so as to form a reflecting-surface. On

the shaft I is secured a disk 4, formed of insulating material, and tothe disk are attached arms 5, which project radially therefrom. To the outer ends of these arms are detachably secured contact-pieces G, having one end embedded in or electrically connected to the pencil 7, formed of magnesia or kaolin or other material which is a non-conductor when cold, but will when heated become a good conductor for electricity. As shown by Fig. 3, the contact-pieces G are made, preferably, in

the form of Hat strips, preferably of platinum or nickel and of a width approximately equal to the width or diameter of the pencil 7,which may be either round, square, or other shape in cross-section. These strips are embedded in the ends of the pencil, so that their edges will be flush with the surface of the pencil; but by the rotation of the shaft the pencil is caused to pass between blocks S, formed of graphite 6o or other conducting material, heldin such relation to the path of movement of the pencil that the blocks will rub along the sides of the pencil and make a deposit from end to end thereof. These blocks S may beheld by any suitable means in proper relation to thepath of movement of the pencil, so that they will rub sufficiently hard thereon to deposita film, as described. A convenient means for supporting these blocks in proper relation to the 7o path of movement of the pencil consist of V spring-plates f1), secu red at one end to the shell or case and having the blocks S attached to their outer ends. Care should be taken that the blocks 8 should be so arranged with rela- 7 5 tion to the path of movement of the pencil and the manner in which the contact-pieces are secured thereto that a deposit of graphite will be made on the exposed edges of the contact-plates and will be continuous therefrom 8o along the pencil from one plate to the other, thereby forming a conductor along the sides of the pencil. The arms 5 are electrically connected by means of wires IO or in any other suitable manner to the spring contactplates I1, which are mounted upon disk I2, formed of insulating material and secured to the shaft l.l On blocks I3 of insulating material are attached spring-plates le, to which are connected the feed-conductors l5. The 9o blocks IIS are secured on the case or shell 3 in such position that the contact-plates 14 will lie in the path of movement of the plates 1I when shifted by the rotation of the shaft I.

The pencil having been properly attached to the arms 5, shaft I is rotated by the knobs IG on the ends of the shaft, so as to cause the pencil to pass between the rubbing-blocks S, and thereby form one or more continuous conducting strips or films along the sides of the roo pencil. As the rotation of the shaft continues the contact-plates Il are brought into electrical contact with the plates 'lf-l, thereby closing the electric circuit, so that a current Will pass to the arms 5 and contact-plates G and thence along the conducting strips or films on the pencil. By the action of this current the pencil will be brought to asu lhcien tly high heat to render it conducting, so that the current passing through the pencil Will heat the same to asufficiently high temperature to render it incandescent.

In order that the Whole of the current may be utilized for renderingthe pencil incandescent and maintaining it in such condition, the film or path of conducting material along the pencil should be rendered practically neutral or ineffective as a conductor so soon as the pencil has become sufficiently heated to become conductive. To this end the film or path may be formed of a material, such as graphite, which will be burned or destroyed by the heat of the pencil, or of a material, such as manganese peroxid, which is rendered non-conductive at high temperatures. Under the term conductor neutralizable at high temperatures7 as herein employed is included any form or construction of conductor connecting the terminals ofthe pencil and arranged in such relation to the pencil as to be effective to heat the latter to a conducting temperature7 but capable of being rendered neutral or ineffective as regards its conducting qualities so soon as the pencil has attained a conductive condition. This neutrality or ineffective condition may be produced by a diversion of the current, a rupture or destruction of the conductor, or the conducting quality of the conductor may be destroyed.

While I have shown and described with a considerable degree of particularity devices for supporting the pencil, for applying a neutralizable strip or film of conducting material along the pencil, and for controlling the electric circuit, the invention as regards the broad terms of the claims is not limited to such construction7 as I consider Within the scope of the invention any means which would suggest themselves` to those skilled in the art for applying a conductor to the pencil in such manner as to form a continuous neutrali/:able path for the electric current from one terminal thereof to the other as Within the scope of this invention.

I claim herein as my invention- A l. In an incandescent lamp, the combination of a pencil or rod formed of a material non conductive at low temperatures but conductive at high temperatures, terminals formed of conducting material, a conductor neutralizable at high temperatures for connecting the terminals and arranged in such relation to the pencil or rod as to heat the rod on the passage of a current to a conducting temperature and mechanism for renewing said conductor from time to time, substantially as set forth.

2. In an incandescent lamp, the combina tion of a pencil or rod formed of a material nonconductive at low temperatures but conductive at high temperatures, terminals formed of conducting materials and mechanism for connecting the terminals of the pencil by a conductor neutralizable at high te1nperatures, the conductor being arranged in such relation to the pencil or rod as to heat the same on the passage of a current to a conductive temperature, substantially as set forth.

In an incandescent lamp the combination of a pencil or rod formed ofa material nonconductive at low temperatures but conductive at high tem peratures7 terminals formed of conducting material, aswitch controlling the circuit of the pencil and means operated by such switch, for connecting the terminals of the pencil by a conductor neutralized at high temperatures, the conductor being arranged in such relation to the pencil o1' rod as to heat the same on a passage of a current to a conducting temperature, substantially as set forth;

Lt. In an incandescent lamp, the combination of a pencil or rod formed of a material non-conductive at low temperatures, butconductive at high temperatures, terminals for said rod or pencil formed of conducting material and mechanism for applying to the rod or pencil a strip or iilm of conducting material extending from terminal to terminal, said strip or film being neutralizable at high ten1- peratures, substantially as set forth.

5. In an incandescent lamp, the combination of a pencil or rod formed of a material non-conductive at low temperatures, but conductive at high temperatures, a holder for a conducting material neutralizable at high temperatures, and means for effecting such a movement of one of said parts on the other as to form a strip or lilm of conducting mate rial on the pencil, substantially as set forth.

6. In an incandescent lamp, the combination of a rotatable shaft provided with radially-projecting arms, a rod or pencil formed of a material non-conductive at low temperature but conductive at high temperature, a holder for a conducting material neutralizable at high temperatures, and means for rotating the shaft, thereby causing the pencil or rod to rub along the conducting material, substantially as set forth.

In testimony whereof I have hereunto set my hand.

REGINAL'D A. FESSENDEN.

Witnesses:

DA1-nvm S. WoLcor'r, F. E. GAITHER.

ICO

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